1. Field of the Invention
The present invention relates generally to roof airbag apparatuses for vehicles and, more particularly, to a roof airbag apparatus for a vehicle which is configured such that even though an air tube which is deployed from a roof panel of the vehicle has a comparatively small volume, it can effectively protect a passenger in the event of a vehicle collision.
2. Description of Related Art
Generally, airbag apparatuses protect the upper bodies of passengers in such a way that the airbag cushions are rapidly inflated by injecting air or gas into airbag cushions when vehicle collisions occur. Such airbag apparatuses are classified into a driver seat airbag apparatus which protects a driver, and a passenger seat airbag apparatus which protects a passenger sitting on the passenger seat.
As shown in FIG. 8B, the passenger seat airbag apparatus includes an inflator 40 which generates gas, an airbag cushion 10 which is inflated by gas supplied from the inflator 40, a housing 50 which houses components, and an airbag door 60.
In the conventional passenger seat airbag apparatus, the airbag cushion 10 is retained in a crash pad 20 under normal conditions. When a vehicle collision occurs, the airbag door 60 is opened in the direction of the windshield by a signal to deploy transmitted from an ACU. Simultaneously, as shown in FIG. 8A, the airbag cushion 10 is deployed into a shape it has when it comes into close contact both with the upper surface of the crash pad 20 and with the windshield.
However, in the conventional passenger seat airbag apparatus having the above-mentioned construction, when the airbag door opens to deploy the airbag cushion, the airbag door strikes the windshield. Thereby, the windshield may be broken.
Furthermore, to reliably protect the passenger from impact, the airbag must have a large capacity that corresponds to the space between the crash pad and the passenger. In the case where the airbag having the large capacity is used, the entire weight of the vehicle increases, and the production cost of the airbag apparatus increases.
Moreover, the designs of the crash pad and the windshield are suited to the kind of vehicle so that they are different between different kinds of vehicles. The difference in design causes variations in the shape and structure of the airbag cushion. This makes it difficult to standardize the passenger seat airbag apparatus.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.